Apparatus for treating paper stock



2 Sheets-Sheet l E. cowLEs APPARATUS FOR TREATING PAPER STOCK July 21, 1953 Filed Nov. 14, 1949 NVE TOR I 7W 7W ATTORNE July 21, 1953 E. COWLES APPARATUS FOR TREATING PAPER STOCK Filed Nov. 14. 1949 2 Sheets-Sheet 2 I Y INVEETOR IIATTOIIQNEY Patented July 21, 1953 APPARATUS FOR TREATING PAPER STOCK Edwin Cowles, Cayuga, N. Y., assignor to The Cowles Company, Princeton, N. J., a corporation of New Jersey Application November 14, 1949, Serial No. 127,164

6 Claims.

This invention relates to apparatus for treating paper stock and pertains more particularly to apparatus for effecting a more complete defibering of paper stock which has previously been subjected to a preliminary but incomplete defibering treatment. Such stock is sometimes referred to as slushed stock. It has been broken down and reduced to a fiowable condition, but still contains a considerable proportion of agglomerates which render it unsuitable for use on a paper making machine without further defibering treatment.

It is an object of this invention to provide an apparatus for defibering such stock quickly and with a minimum consumption of power. The defibering of the stock may or may not be accompanied by other actions on the individual fibers such as hydration and cutting, depending on the nature and setting of the working elements of the apparatus hereinafter described.

Other objects and advantages of the invention will appear hereinafter.

A preferred embodiment of the invention selected for purposes of illustration is shown in the accompanying drawings, in which,

Figure 1 is a front elevation of the apparatus, partly broken away.

Figure 2 is an enlarged sectional view of one side of the apparatus.

Figure 3 is an enlarged plan view of the rotor and stator rings showing the working relationship of the working elements.

According to the present invention, the fibrous material which is being treated is picked up by the advancing edge of a moving element which is relatively thin, so that the fibrous material may staple over the advancing edge and be held thereon while being moved toward and into a slot formed between two fixed elements. The clearances between the moving element and the fixed elements are small so that the stapled material may be worked between the moving element and the fixed elements as the moving element moves through said slot.

In order to secure most effective working of 'the material, the clearances between the moving Therefore the fixed elements are preferably ar- ..ranged to resist deflection; and if the clearances between the moving element and the fixed elements on either side are substantially equal, the forces acting laterally on the moving element as it enters and moves through the slot will be subtantially equal, so that any tendency toward deflection is minimized.

In the preferred embodiment of the invention a plurality of sets of moving elements are provided and a plurality of sets of fixed elements are provided to form sets of slots through which the moving elements may move. In such arrangement it is desirable that the fixed elements also be relatively thin, and in the preferred embodiment the individual elements of the sets of fixed and moving elements are aligned so as to be mutually and reciprocally resistant to deflection as hereinafter explained.

Referring to the drawings, the preferred embodiment of the apparatus comprises a casing I having an inlet 2 and an outlet 3. Mounted within the casing is a stack of stator rings 4 spaced apart by spacer rings 5, the entire stack assembly being held tightly between upper and lower clamp rings 6 and l by means of bolts 8. The lower ring 1 may be welded or otherwise se- A cured to the inner wall of the casing, but the upper ring 6 is spaced therefrom and movable with respect thereto. If desired, a packing ring 9 may be inserted between the ring 6 and the wall of the casing.

Also mounted within the casing is a rotor comprising a rotatable shaft Ill carrying a stack of rotor rings ll spaced apart by spacer rings l2, this stack assembly being held tightly between upper and lower clamp members I3 and M by bolts l5. The pins [6, threaded into the lower clamp member M, are merely guide pins which accurately locate and center the rings II and [2.

The stator rings 4 and the rotor rings II and their operative relationship are illustrated in detail in Figure 3. As there shown, the outer perimeter of the rotor rings are of less diameter than the inner perimeters of the stator rings, thereby providing spaces through which the stock may move. The rotor rings are provided, however, with a plurality of moving elements in the form of blades ll projecting outwardly beyond their outer perimeters, said blades being of a length to overlap slightly the inner perimeters of the stator rings. Likewise, the stator rings are provided with a plurality of fixed elements in the form of blades [8 projecting inwardly beyond their inner perimeters, said blades being of a length to overlap slightly the outer perimeters of the rotor rings.

The blades of the rotor are interleaved with the blades of the stator, as shown in Figures 1 and 2, the arrangement being such that each rotor blade of any given rotor ring moves through slots formed between the stator blades of the stator rings on either side thereof. Further, there is some slight clearance between opposed faces of the rotor and stator blades. These clearances are preferably equal throughout the stacks and may be varied, as desired, by varying the thickness of the spacer rings and i2. These clearances should preferably be less than and it has been found that clearances of & give good results when treating stock at a consistency of 1% to 2 At higher consistencies a wider clearance may be desirable or at lower consistencies a smaller clearance may be desirable.

The advancing or working edges IQ of the rotor blades are preferably straight edges which are slightly inclined to a true radius. Likewise the Working edges 20 of the stator blades are slightly inclined to a true radius, but in the opposite direction. Therefore, as the rotor blades advance into working relationship with the stator blades, the action is similar to what would be described as a shearing action if the blades were in actual contact.

In the operation of the apparatus, as the rotor blades move through the slots between the stator blades, each blade of the rotor works the stock against the stator blades immediately above and below it, and while the blade is advancing from working engagement with one pair of stator blades to a position close to working engagement with the next pair of stator blades, picks u an accumulation of fibrous material which staples over the advancing edge 58. The conditions for accumulation of fibers on the advancing edges in this manner are extremely favorable, for the velocity of the'advancing edges is very high as compared with the velocity of flow of stock through the spaces between the outer perimeter of the rotor ring'and the inner perimeter ofthe stator ring, with the result that the velocities of stock movement relativeto the two faces of the rotor blades are substantially equal.

The rotation'of the rotor stack induces some rotary movement of the stock in said spaces which also tends to'c'ause accumulation of some fibrous material on the front edges 28 of the stator blades during the periods between successive workingengageinents with the rotor blades.

As a result of these accumulations cf'fibers on the edges of both the rotor and stator blades, when the rotor blades come into working engagement with the "stator blades, the accumulated fibers are subjected to vigorous mechanical action which quickly pulls or tears apart any agglomerates and reduces the same to individual fibers.

Each blade or each stator ring is aligned axially with the corresponding blade of each other stator ring of the stator stack. Likewise, each blade of each rotor ring is aligned axially with the corresponding blade or" each other rotor ring of the rotor stack. This arrangement permits the use of very thin rotor and stator rings without danger of bending or distorting the blades thereof for the forces acting on opposite faces of the aligned blades are substantially equalized throughout the stack. Thus, whenever a rotor blade carrying an accumulation of fibers moves into working engagement with the stator blades lying immediately above and below it, the pressure on the upper face or" the rotor blade will .be substantially.

4 equal to the pressure on the lower face of that blade. Likewise, the pressure on the upper face of any stator blade will be substantially equal to the pressure on the lower face of that stator blade.

In the embodiment illustrated, the number of stator rings exceeds the number of rotor rings by one, so that the stator rings at each end of the stack lie outside the end rings of the rotor stack. At each end of the stack of stator rings, the stator blades of the end rings are supported by rigid supports. Thus, at the top of the stack, the upper clamp ring 6 is provided with a plurality of inwardly projecting members 2] of substantially the shape of the blades and similarly spaced, which,

being the full thickness of the clamp ring support the stator blades at the top of the stack. At the bottom of the stack, a special ring 22 is provided, seated on the lower clamp ring 1, and provided with inwardly projecting members 23 of substantially the shape of the blades, and similarly spaced, which are of sufiicient thickness to support the blades at the bottom of the stack.

As a result of this arrangement, the blades of both the rotor and stator stacks, while thin and somewhat flexible, are, in operation, substantially resistant to deflection, for as previously pointed out, the forces acting on opposite sides of both rotor and stator blades are substantially equalized within the stacks, and the end blades of the stator stacks are supported.

The use of thin rings and blades is advantageous for several reasons. First, it permits the use of smaller, lighter and cheaper stacks and reduces the size, weight and cost of the apparatus. Second, and more important, the thinner the blades the more emcient theyare in picking up and retaining accumulations of fibers. Third, the thinner the blades, the less the turbulence created and the less the hydraulic losses due to turbulence and skin friction. For these reasons, it is preferred that the rings and blades of both rotor and stator should not exceed in thickness and in most cases even better results are obtained with thicknesses between and fl If desired, each of the blades of the rotor, or stator, or both, may be provided with a series of perforations 2 2 in the rotor, 25 in the stator, which, in effect, roughen the faces of the blades and increase the working efiect on the material.

It will be noted that since the outer ends of the rotor blades I! overlap the inner peripheries of the stator rings, they are running in channels which are closed at the back by the spacer rings 5. This arrangement is advantageous in preventing deflection of the rotor blades while moving from working engagement with one set of stator blades to the next. In order to keep these channels clear, the outer edges 23 of the rotor blades are cut back, i. e. they cross the radius at an angle less than with the result that as they move along said-channels, they produce a suction eifect causing eddy currents and turbulence within the channels which keep the channels clear.

In the preferred embodiment the rotor rings and stator rings are each provided with an even number of blades, but the stator rings have a greater number of blades than the rotor rings. By the latter provision I insure that the blades around the periphery of the rotor rings come into working engagement with thestator blades successively rather than simultaneously as would be the case if equal numbers of blades were used, thereby avoiding excessive stresses and excessive vibration. By the former provision, I insure similar working conditions at diametrically opposite points of the rotor and stator rings at all times, thereby preserving a condition of balance.

The stock to be treated is caused to flow through the apparatus in any desired manner, as by gravity or by a suitable pump. In the embodiment illustrated the upper clamp member [3 of the rotor carries a plurality of vanes 21 which may be removed from time to time.

It will be understood that while the invention has been particularly described with reference to an apparatus for defibering paper stock, the said apparatus may also be useful for securing other refining effects and may also beused for the defibering, disintegrating or otherwise treating other materials.

It will also be understood that the invention may be variously modified and embodied Within the scope of the subjoined claims.

I claim as my invention:

1. Apparatus for treating paper stock, comprising, a stack of spaced rotor rings, a stack of spaced stator rings, said stacks of rings being concentrically arranged, the outside perimeter of said rotor rings having a diameter less than that of the inside perimeter of said stator rings so as to provide space therebetween, each of said rotor rings having circumferentially spaced blades projecting outwardly from its outer perimeter across said space, and each of said stator rings having circumferentially spaced blades projecting inwardly from its inner perimeter across said space, said rotor blades overlapping and being interleaved with said stator blades, the spacing between said rotor and stator rings being such as to provide relatively small but substantially equal clearances between opposed rotor and stator blade faces throughout the stacks.

2. Apparatus according to claim 1 in which each of the stator rings is provided with an equal number of blades with corresponding blades aligned axially throughout the stator stack, and in which each of the rotor rings is provided with an equal number of blades with corresponding blades aligned axially throughout the rotor stack.

3. Apparatus according to claim 1 in which each of the stator rings is provided with an equal number of blades with corresponding blades aligned axially throughout the stator stack, in which each of the rotor rings is provided with an equal number of blades with corresponding blades aligned axially throughout the rotor stack, in which the number of stator rings exceeds the number of rotor rings by one, in which the stator rings at each end of the stack lie outside the end rings of the rotor stack, and in which the blades of the end stator rings are supported against distortion by rigid supporting members.

4. Apparatus accordingto claim 1 in which the outer edges of the rotor blades are cut back to cross the radius at an angle less than 5. Apparatus for treating paper stock, comprising, a moving element comprising a plurality of relatively thin blades each having side surfaces parallel 'to its direction of movement and an advancing edge substantially at right angles to its direction of movement, said blades being stacked in a row, and a plurality of spaced'fixed elements stacked in a row and having opposed spaced surfaces between which said moving elements may pass, the clearances between the side surfaces of saidmoving elements and the opposed surfaces of said fixed elements being substantially equal.

6. Apparatus according to claim 5 in which the thickness of each of said moving blades is less than and the clearances between said surfaces are less than EDWIN C'OWLES.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain Nov. 24, 1938 

